The long-term objective of this research is to elucidate the mechanisms of neurotransmitter release, alterations of which probably are the basis of several mental illnesses. This project proposes to examine contractile proteins in nerve endings which may be involved in evoked release. Synaptosomes will be incubated under various conditions of release and then subfractionated. The existence, functional status and polymerization state of contractile proteins in the synaptosomal subfractions will be determined. Changes in these parameters will be correlated with or dissociated from the quantities of released neurotransmitters to examine the hypothesis that synaptic contractile proteins provide the mechanism for moving the synaptic vesicle to the synaptic plasma membrane during evoked release.